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Archive   : SNIP9503.ZIP
Filename : WB_FCOPY.C

/*
** by: Walter Bright via Usenet C newsgroup
**
** modified by: Bob Stout based on a recommendation by Ray Gardner
**
** modified by: David Gersic to deal with binary files
**
** There is no point in going to asm to get high speed file copies. Since it
** is inherently disk-bound, there is no sense (unless tiny code size is
** the goal). Here's a C version that you'll find is as fast as any asm code
** for files larger than a few bytes (the trick is to use large disk buffers):
**
** To compile file_copy(), define Afilecopy=1 on the command line
** To compile file_append(), define Afileappe=1 on the command line
*/

#include
#include
#include

#if !defined(__ZTC__) && !defined(__TURBOC__)
#include
#endif

#include

#if Afilecopy
int file_copy(char *from, char *to)
#else
int file_append(char *from, char *to)
#endif
{
int fdfrom,fdto;
int bufsiz;

fdfrom = open(from,O_RDONLY|O_BINARY,0);
if (fdfrom < 0)
return 1;
#if Afileappe

/* Open R/W by owner, R by everyone else */

fdto=open(to,O_BINARY|O_CREAT|O_APPEND|O_RDWR,S_IREAD|S_IWRITE);
if (fdto < 0)
goto err;
#else
fdto=open(to,O_BINARY|O_CREAT|O_TRUNC|O_RDWR,S_IREAD|S_IWRITE);
if (fdto < 0)
goto err;
#endif

/* Use the largest buffer we can get */

for (bufsiz = 0x4000; bufsiz >= 128; bufsiz >>= 1)
{
register char *buffer;

buffer = (char *) malloc(bufsiz);
if (buffer)
{
while (1)
{
register int n;

n = read(fdfrom,buffer,bufsiz);
if (n == -1) /* if error */
break;
if (n == 0) /* if end of file */
{
free(buffer);
close(fdto);
close(fdfrom);
return 0; /* success */
}
if (n != write(fdto,buffer,(unsigned) n))
break;
}
free(buffer);
break;
}
}
err2: close(fdto);
remove(to); /* delete any partial file */
err: close(fdfrom);
return 1;
}